Twist drill grinding fixture



Oct. 25, 1949. T N C, sMn-H TAL 2,486,335

TWIST DRILL GRINDING FIXTURE Filed Jan. 14, 1946 2 She'S-Sheel'.v 1

Oct. 25, 1949. N. c. SMITH E TAL 2,486,335

TWIST DRILL G'RINDING FIXTURE Filed Jan. 14, :.L94e l A:2' sheets-sheet 2 Patented Oct. 25, 1949 TWIST DRILL GRINDING FIXTURE Neil C. Smith, Minneapolis, and Wallace E. J ohn son, Robbinsdale, Minn.; said Johnson assignor Application January 14, 19116, Serialv No. 641,088

Claims.

Our present invention relates tov improvements in grinding fixtures for regrinding twist drills.

It is well known in shop practice that in order to obtain the maximum efci'ency and life from a twist drill, it is absolutely essential that it be properly ground at the point. The two cutting edgesV must be, iirst, of exactly the same length and, second', of the same inclination to the axis of the drill.. Another important thing to be considered in grinding drill points is the angle of lip clearance or the proper backing off of the cutting edges.

An objective of this invention is to provideA a twist drill grinding xture having novel means for adjusting a twist drill relative to a grinding wheel, whereby one of its lips may be ground to a predetermined angle to the axis of the drill and at the same time, the respective lip will be ground to a predetermined angle at its cutting edge for lip clearance or the proper backing off of the cutting edge.

Another object of this invention is to provide a twist drill grinding fixture having novel means for raising or lowering a drill for engagement with a grinding Wheel at a predetermined point.

Still another object of this invention is to provide a twist drill grinding xture on which a drill may be repositioned after grinding one of itsl lips so that the other lip will be ground at exactly the same angle and length as the rst noted lip.

Other objects of the invention will be apparent from the following description, reference being had to the accompanying drawings.

To the aboveend, the invention consists of the novel devices and combination of devices hereinafter described and defined in the claims.

In the accompanying drawings,l which illustrate the invention, like characters indicate like parts throughout the several views.

Referring to the drawings:

Fig. 1 is a side elevation of the twist drill xture, attached toa grinder fragmentarily shown, a portion of said fixture being broken away and sectioned;

Fig. 2 is a detail View partly in plan and partly in section taken on line 2-2 of Fig. 1;

Fig. 3 is a detail view principally in section taken on the line 3-3 of Fig. 2;

Fig. 4 is a view partly in front end elevation and' partly in section taken on the line 4-4 of Fig. 1`;

Fig. 51s a topI view of the grinding fixture removed fromits support;

Fig. 6 is a fragmentary front end elevation of the parts shown in Fig. 5, on arr enlarged scale; and

Figs. '7, 8 and 9 are detail Views with someY parts sectioned on the lines T T, 8`8 and 9`9- of Fig. 5, respectively.

For the purpose of showing the grinding fixture in working position, there is shown in Fig.y 1

a fragment of a grinder, indicated as an entirety- Y by the numeral iI, with the exceptionl of its grinding wheel I2 and the Wheel guard I3* having a horizontal way |14'. This way I4'l is below the axis of the wheel I2 and parallel thereto. The grinder Il may be either of the bench or pedestal type.

The improved twist drill grinding fixture includes a body member I 5y having a long rear ex'- tension I6 in the form of an angle bar. In the top of the body member I5: is a trough-like drill rest I'l that is V-shaped inY cross-section and the side members thereof are designated by the numerals i8' and I9. The angle'bar extension I6 is arranged to form a V-shaped trough that is entirely below the drill rest I'I.. This drill rest I1 and the extension I6 are upwardly inclinedl in parallel planes andl the bottoms thereofI are in the same vertical plane.

On the under side of the body member I51isf a hub 20 having therein a vertical borey 2 I. It is important to note that the bore 2| is laterally offset from a vertical plane in which thelbottoms of the drill rest l'l and the extension I6 lie, see broken line :c-:ck on Fig. 4.

The body member I5v is. supported on a stud 22'v to swing about a vertically disposed axis. Thisy stud 22, at its upper end portion, extends into the bore 2| andthe body member lfrests` on the upper end thereof. The stud.v 22. below the hub 20 has screw-threaded engagement with a nutacting member 23. A lock nut 24 is applied toI the stud 22 above the member 23.' and normallyv impinges the same.

The nut-acting member' 2'3 has a radialf extension 251 that i's pivoted tov a short horizontal shaft 26, at one of its end portions, by a nutequipped bolt 2l to swing about` a horizontal axis. The end portion of the shaft 2B" that overlaps' the member 23 is Semi-circular in cross-section and its flat face bears on the member 23, see Fig.

bolt 21, see Fig. 3. A pair of opposing set-screws have screw-threaded engagement with the member 23, extend into the slot 29 and impinge the bolt 28 at diametrically opposite points.

The shaft 26 extends transversely under the grinding wheel I2, parallel to the axis thereof and is mounted in a hub 3| on the lower end of a bracket 32 for compound endwise and turning movements. A set-screw 33 has screw-threaded engagement with the hub 3I impinges the shaft 26 and holds said shaft where adjusted. The bracket 33, at its upper end portion, has a horizontal groove 34 in which the way I4 extends and supports said bracket for straight line horizontal adjustment relative to the grinding wheel I2. A nut-equipped stud 35 on the way I4 extends through a horizontal slot 36 in the bracket 32 and holds said bracket where adjusted on the way I4.

A secondary drill rest 3'I is mounted on the extension I6 for adjustment toward or from the drill rest I'I. The bottom of the drill rest 3l is V-shaped in cross-section, snugly fits in the extension I6 and supports said rest for sliding adjustment longitudinally thereon. The top of the drill rest 3l is V-shaped in cross section and the side members thereof are in the same planes as the side members I8 and I9 and the bottoms of said two drill rests are aligned. Integral with the drill rest 3l is a lug 38 that overlaps one of the side members of said rest and is spaced outwardly therefrom. A set-screw 39 has threaded engagement with the lug 38, impinges the respective side member of the extension I6 and holds said rest where adjusted thereon, see Fig. 8.

An adjustable drill stop 4I] is mounted on a clamp 4I which in turn is mounted on the extension I6 for longitudinal adjustment thereon. This clamp 4I has a V-shaped passageway l2 through which the extension I6 extends. A set-screw 43 has threaded engagement with theclamp l I, impinges the extension I6 and holds said clamp where adjusted thereon. The clamp 4I is bifurcated to afford a pair of upstanding ears 44 that extend transversely of the extension I6. The stop 46 is in the form of a disk having on its back an axially aligned screw stud 45 that has threaded engagement with the ears 44. Applied to the stud 45 between the ears M is a lock nut 46 that impinges one of said ears.

The outer end portion of the side member I8 is rounded at 4l for a purpose that will presently appear. Integral with the outer end portion of the side member I9 is a nut-acting lug 48 that extends outwardly of the ends of said member. A long gauging screw 4S has threaded engagement with the lug 48 and is provided for holding a drill a: as shown in Fig. 6.

To regrind a drill, the same is placed on the drill rests I'I and 3l, as shown in Fig. 1, and which rests center the drill as shown in Fig. 6. The stop is adjusted to position the drill with its point projecting outwardly of the drill rest II for contact with the grinding wheel I2. Next, the bolt 38 is loosened and the member 23 adjusted by the screws 30 to tilt the xture and hence the drill as,

4 wardly from the axis of said wheel. In the lower end of the stud 22 is a nick for a screw-driver by which said stud may be rotated and endwise adjusted to raise or lower the xture to position the point of the drill at the desired point on the grinding wheel I2.

To grind one of the lips of the drill, the xture is turned on the stud 22 from a position in which it extends in a plane perpendicular to the face of the grinding wheel I2, toward the right. During this movement of the fixture, the lateral offset of said fixture Irelative to the stud 22 will cause Said drill to be ground at the proper angle of lip clearance, By adjusting the bracket 32 on the way I 4, the fixture maj7 be 'moved laterally to position the point of the drill the desired distance from the periphery of Ithe grinding wheel I2. The rounded end Il of the side member I8 permits the required lateral movement of the xture while grinding the drill. To grind the -other lip of the drill, it is only necessary' to return the xture to its original position, lift the drill :c from the rests I'I fand 3l, give the same a one-half turn and replace the drill :c in the rests I'I and 3l with its outer end against the stop 40 and its web against the gauging screw 39. This positions the drill :l:

lin the rests Il and 37 so that the other lip of said drill will be ground exactly like the rst lip therein a Vertical plane to position said drill` so that The drawings illustrate a commercial form of the invention, but it will be understood that the same is capable of certain modiiications as to details of construction, arrangement and combination of parts within the scope of the invention herein disclosed. y

What we claim is:

l. In a device of the class described, a supporting member, a member mounted on the supporting member to turn about a horizontal axis and having a vertically disposed stud, an inclined drill rest pivotally mounted on the stud, said member having a vertically disposed slot, a fixed pin on the supporting member and extending into the slot, and a pair of opposing set-screws having threaded engagement with the member and impinging the pin on opposite sides, and operable to vary the inclination of the drill rest.

2. In a device of the class described, a supporting bracket, :a horizontally disposed shaft mounted on the bracket for endwise adjustment, the shaft at its outer end portion having a at side, a member attached to the shaft at its flat side to turn about a horizontal axis, said member having a vertically disposed slot, a nut-equipped bolt on the shaft and extending through said slot and normally holding the member from turning about said axis, a pair of opposing set-screws having threaded engagement with the memberand impinging the bolt on opposite sides, a vertically disposed stud having screw-threaded engagement with the member, and a drill rest pivotally mounted on the stud. A

3. In a device of the class described, a'kbody member having a V-shaped drill rest, a lug on one of the sides of said rest and extending outwardly and inwardly thereof, and a gauging screw having threaded engagement with said lug for direct engagement with the web of a drill on said rest.

4. In a device of the class described, a supporting member, :an adjusting member intermediately pivoted to the supporting member for movement in a vertical plane and having in one end portion a vertical bore and in its other end portion a vertical slot, a stud in said bore 'and having screwthreaded engagement with the adjusting mem--v bei', a body member turnably mounted on the stud and having an inclined drill rest, yand a pair of UNITED STATES PATENTS opposing adjusting screws having threaded en- Number Name Date gagernent with the adjusting member and inming- 411,845 Walker Oict. 1, 1889 ing the pin on opposite sides thereof and operable 5 584,114 Hill J uney 8, 1897 to change the inclination `of the drill rest. 622,212 Dutton Apr. 4, 1899 5. The structure'defined in claim 4 in which 751,198 Parpart Feb. 2, 1904 the center of the drill rest is offset from the 'pro- 1,106,692 Wirrcrantz Aug. 11, 1914 jected axis of the stud. 1,363,194 De Koning Dec, 21, 1920 NEIL C. SMITH- lo 2,065,847 Young Dec. 29, 1936 WALLACE E. JOHNSON. FOREIGN PATENTS REFERENCES CYTED' Number Country Date The following references are of record in the 14,432 Great Brltam June 19 1909 me of this patent: 15 123,513 Great Britain Feb.27,191s 

